Zaharakis has committed to a new three-year deal that will see him wearing the red and black until the end of the 2014 season, while Colyer has signed a two-year contract that will see him through to the end of the 2013 season.
General manager of football operations Paul Hamilton said he was thrilled to see a number of emerging players committing to the future of the football club.
""We feel both David and Travis will have a strong role to play in Essendon's next period of sustained success and we are obviously very pleased to have them commit to the club,"" Hamilton said.
""Both players have improved dramatically this season - including David winning his first Crichton medal in only his third season of football - and we feel they both can develop further over the next two years to establish themselves as integral members of the Essendon midfield.""
Zaharakis, 21, was drafted to Essendon via selection 23 in the 2008 AFL National Draft. He has played 53 games and kicked 57 goals.
